Distance between tracks

Hey,
I'm building a board that has some fairly high voltages. Well, high for a PCB anyway. Naturally I was interested in seeing how far apart I need to place the tracks to stop arcing/make it legal.

I came across this formula on the net: Distance between tracks = 0.023" + (0.0002" * peak volts).

Can anyone confirm this? Does anyone know what the international standards (European/American) say?

Thanks

High is not a value, high is a relative perspective, define your value of high or we can't help. Standard PCB trace ratings are only for 'low' voltages.

KingKrak said:

Hey,
I'm building a board that has some fairly high voltages. Well, high for a PCB anyway. Naturally I was interested in seeing how far apart I need to place the tracks to stop arcing/make it legal.

I came across this formula on the net: Distance between tracks = 0.023" + (0.0002" * peak volts).

Can anyone confirm this? Does anyone know what the international standards (European/American) say?

Thanks

Click to expand...

hi,
Look at this PCB Design Tutorial

KingKrak said:

Hey,
I'm building a board that has some fairly high voltages. Well, high for a PCB anyway. Naturally I was interested in seeing how far apart I need to place the tracks to stop arcing/make it legal.

I came across this formula on the net: Distance between tracks = 0.023" + (0.0002" * peak volts).

Can anyone confirm this? Does anyone know what the international standards (European/American) say?

Thanks

Click to expand...

completely bogus.

legally, per CE61601-1 (CE medical, double insulation, which i believe is still good for defib proof, at 240VAC), you are only required to have 8mm (0.315") creapage (over a surface like a component or a PCB). the formula says over 1" (spec requires 5KV insulation)

at the other end it is limited by etching technology. I regularly design with 0.008" trace width and spacing, which is legally good for voltages below... well i forget off hand if it is 32V or 50V. more expensive processes can do finer pitch than that.

dan

Thanks for the replies guys. I am still a bit confused. Ubergeek63, you said for 240VAC you are required to have 8mm. This is also in the document that ericgibbs suggested I read. Yet...

I have sitting in front of me right now a 1200V rated IGBT that has a pin spacing of 2.5mm. This IGBT is produced by a major multinational manufacturer. I also have another PIM type IGBT that has a pin spacing of only 6.4mm between 2 phases of 415VAC 3 phase. This makes it kind of hard to put tracks to the pins.

After this I took a look at a few circuit boards that I have sitting around our workshop. One was out of a variable frequency drive that operates at 415VAC 3 phase. I measured the power tracks between 2 phases and it was only 5mm. This VFD is from a very reputable worldwide manufacturer.

So... does anyone know how I can run tracks to these things? About the best I can do is 40mil (1mm) between tracks and still have a track thick enough to carry the current.

well i would have to look it up again... 8mm is safety isolation between the power circuit and the user. the spec is more lenient for "lines of oposite polarity", 3mm @ 240V i believe it is. common industry practice is to stagger the pins to get the spacing.

415V would be more ... 9mm maybe ... i am at home now ...